Patent literature 1 describes a power supply system for supplying electric power to a vehicle in a non-contact manner which can execute a safe and efficient power supply without allowing foreign matters to enter a space defined between a power supplying unit and a power receiving unit. In this system, an electrically insulating isolation member is provided to prevent foreign matters from entering the space between the power supplying unit and the power receiving unit. The isolation member is either embedded in a parking space or accommodated in an interior of the vehicle, and when supplying electric power to the vehicle, the isolation member is caused to project into the space via a movable portion. The isolation member is formed into a rectangular frame shape (in other words, a cylindrical shape) which is opened upwards and downwards by using four isolation members of an electrically isolating material so as to surround a space defined by respective projected planes of the power receiving unit and the power supplying unit when the power receiving unit and the power supplying unit are disposed to face each other. Further, a vertical length of the isolation member (in other words, a height of the isolation member in an axial direction thereof) is set at a predetermined dimension which is slightly smaller than a space defined by a road surface of the parking space where the power supplying unit is provided and a bottom surface of the vehicle.